Exposure apparatus, exposure method, and method for producing device

ABSTRACT

An exposure apparatus fills an optical path space of an exposure light beam with a liquid, and exposes a substrate by irradiating the substrate with the exposure light beam via a projection optical system and the liquid. A first optical element of the projection optical system is provided with a removing device for removing foreign matters in a space inside of the concave surface portion. Immersion exposure is performed by permitting the exposure light beam to excellently reach an image plane via the projection optical system and the liquid.

TECHNICAL FIELD

The present invention relates to an exposure apparatus, an exposuremethod, and a method for producing a device, wherein a substrate isexposed through a liquid.

BACKGROUND ART

An exposure apparatus, which performs the projection exposure onto aphotosensitive substrate with a pattern formed on a mask, is used in thephotolithography step as one of the steps of producing microdevices suchas semiconductor devices, liquid crystal display devices, and the like.The exposure apparatus includes a mask stage for supporting the mask anda substrate stage for supporting the substrate. The pattern of the maskis subjected to the projection exposure onto the substrate via aprojection optical system while successively moving the mask stage andthe substrate stage. In the microdevice production, it is required torealize a fine and minute pattern to be formed on the substrate in orderto achieve a high density of the device. In order to respond to thisrequirement, it is demanded to realize a higher resolution of theexposure apparatus. A liquid immersion exposure apparatus, in which aliquid immersion area is formed by filling the space between theprojection optical system and the substrate with a liquid to perform theexposure process through the liquid of the liquid immersion area, hasbeen contrived as one of means to realize the high resolution, asdisclosed in the patent literature 1.

-   Patent Literature 1: the International Publication No. 99/49504.

DISCLOSURE OF THE INVENTION Task to be Solved by the Invention

In the liquid immersion exposure apparatus, the higher the refractiveindex of the liquid for filling the optical path space for the exposurelight beam therewith is, the more improved the resolution and the depthof focus are. Accordingly, it is demanded to realize a liquid immersionexposure apparatus based on the use of the liquid having the highrefractive index as described above.

The present invention has been made taking the foregoing circumstancesinto consideration. A first object of the present invention is toprovide an exposure apparatus, an exposure method, and a method forproducing a device based on the use of the exposure apparatus and theexposure method, wherein it is possible to realize the liquid immersionexposure by a liquid having a high refractive index. A second object ofthe present invention is to provide an exposure apparatus, an exposuremethod, and a method for producing a device based on the use of theexposure apparatus and the exposure method, wherein an exposure lightbeam is successfully allowed to arrive at an image plane through aliquid.

Solution for the Task

In order to achieve the objects as described above, the presentinvention adopts the following constructions corresponding to FIGS. 1 to12 as illustrated in embodiments. However, parenthesized symbols affixedto respective elements merely exemplify the elements by way of example,with which it is not intended to limit the respective elements.

According to a first aspect of the present invention, there is providedan exposure apparatus (EX) which exposes a substrate (P) by radiating anexposure light beam (EL) onto the substrate (P) through a liquid (LQ);the exposure apparatus comprising a projection optical system (PL) whichincludes a plurality of optical elements, at least one (LS1) of theplurality of optical elements having a concave surface portion (2)making contact with the liquid; and a removing device (40) which removesa foreign matter in a space inside of the concave surface portion (2).

According to the first aspect of the present invention, at least oneoptical element for constructing the projection optical system has theconcave surface portion which makes contact with the liquid. Therefore,the angle of incidence of the exposure light beam can be reduced at theinterface between the liquid and the optical element, and the exposurelight beam is successfully allowed to arrive at the object (substrate orsubstrate stage) arranged on the image plane of the projection opticalsystem or in the vicinity thereof. Even when any foreign matter ispresent in the space inside of the concave surface portion of theoptical element which makes contact with the liquid, the foreign matteris removed by the removing device. Therefore, it is possible to allowthe exposure light beam to satisfactorily arrive at the image plane ofthe projection optical system or the position disposed in the vicinitythereof.

According to a second aspect of the present invention, there is providedan exposure apparatus (EX) which exposes a substrate (P) by radiating anexposure light beam (EL) onto the substrate (P) through a liquid (LQ);the exposure apparatus comprising a projection optical system (PL) whichincludes a plurality of optical elements (LS1 to LS5) and which has afirst optical element (LS1) included in the plurality of opticalelements and disposed closest to an image plane of the projectionoptical system, the first optical element (LS1) having a concave surfaceportion (2) which makes contact with the liquid (LQ); wherein arefractive index of the liquid with respect to the exposure light beamis higher than a refractive index of the first optical element.

According to the second aspect of the present invention, the liquid isused, which has the refractive index higher than the refractive index ofthe first optical element disposed closest to the image plane of theprojection optical system with respect to the exposure light beam.Accordingly, it is possible to greatly improve the resolution and thedepth of focus. The first optical element has the concave surfaceportion which makes contact with the liquid. Therefore, it is possibleto allow the exposure light beam to satisfactorily arrive at the imageplane of the projection optical system or the position disposed in thevicinity thereof.

According to a third aspect of the present invention, there is provideda method for producing a device, comprising using the exposure apparatus(EX) as defined in any one of the aspects described above. According tothe third aspect of the present invention, it is possible to provide thedevice having the desired performance.

According to a fourth aspect of the present invention, there is providedan exposure method for exposing a substrate by radiating an exposurelight beam onto the substrate (P) via a liquid (LQ) and an opticalelement (LS1) having a concave surface portion (2) which makes contactwith the liquid (LQ); the exposure method including removing a foreignmatter from the liquid (LQ) in the concave surface portion (2) of theoptical element; and exposing the substrate (P) by radiating theexposure light beam onto the substrate via the optical element (LS1) andthe liquid (LQ). According to this exposure method, the surface of theoptical element which makes contact with the liquid is the concavesurface. Therefore, the light beam, which is inclined with respect tothe optical axis of the optical element, successfully has the reducedangle of incidence (angle of incidence toward the liquid) at theinterface between the liquid and the optical element. Therefore, evenwhen the refractive index of the liquid is higher than the refractiveindex of the optical element, it is possible to allow the outermost beamof the light flux (convergent light flux) to come into the liquid aswell.

According to a fifth aspect of the present invention, there is providedan exposure method for exposing a substrate (P) by radiating an exposurelight beam (EL) onto the substrate (P) via a liquid (LQ) and an opticalelement (LS1) having a concave surface portion to make contact with theliquid; the exposure method including supplying the liquid (LQ) to aspace between the substrate (P) and the concave surface portion (2) ofthe optical element (LS1), the liquid (LQ) having a refractive indexhigher than a refractive index of the optical element; and exposing thesubstrate by radiating the exposure light beam onto the substrate (P)via the optical element (LS1) and the liquid. According to this exposuremethod, the exposure is performed through the liquid having therefractive index higher than the refractive index of the optical element(LS1). Therefore, it is possible to increase the numerical aperture NAfor the optical element and the light radiation system (projectionoptical system) including the optical element, and it is possible toimprove the resolution and the depth of focus. The reflection of theexposure light beam at the interface between the liquid and the opticalelement, which tends to occur as the numerical aperture NA is increased,is suppressed by the concave surface portion provided at the portion ofthe optical element which makes contact with the liquid.

According to a sixth aspect of the present invention, there is provideda method for producing a device; including exposing a substrate by theexposure method as defined in the fourth or fifth aspect; developing theexposed substrate; and processing the developed substrate. According tothis production method, it is possible to provide the high densitydevice having the desired performance.

EFFECT OF THE INVENTION

According to the present invention, it is possible to allow the exposurelight beam to satisfactorily arrive at the image plane or the positionin the vicinity thereof. It is possible to perform the accurate exposureprocess, and it is possible to produce the device having the desiredperformance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic arrangement illustrating an exposure apparatusaccording to a first embodiment.

FIG. 2 shows a magnified view illustrating those disposed in thevicinity of a first optical element.

FIG. 3 shows an arrangement illustrating a liquid supply mechanism.

FIG. 4 shows a removing unit.

FIG. 5 shows a state in which the removing unit removes foreign matters.

FIG. 6 shows a state in which a detection unit detects any foreignmatter.

FIG. 7 shows a magnified view illustrating main components according toa second embodiment.

FIG. 8 shows a schematic arrangement illustrating an exposure apparatusaccording to a third embodiment.

FIG. 9 shows a plan view illustrating stages shown in FIG. 8 as viewedfrom an upper position.

FIG. 10 shows the operation of the exposure apparatus according to thethird embodiment.

FIG. 11 shows a flow chart illustrating exemplary steps of producing amicrodevice.

FIG. 12 shows a flow chart illustrating a procedure of an exposuremethod according to the present invention.

PARTS LIST

1: liquid immersion mechanism, 2: concave surface portion, 10: liquidsupply mechanism, 18: supply port, 19: mixing unit, 20: liquid recoverymechanism, 28: recovery port, 40: removing unit, 43: suction port, 44:driving mechanism, 50: detection unit, 70: nozzle member, CONT: controlunit, EL: exposure light beam, EX: exposure apparatus, LQ: liquid, LS1:first optical element, P: substrate, PL: projection optical system, PST(PST1): substrate stage, PST2: measuring stage, PSTD: substratestage-driving unit, T1: lower surface.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be explained below withreference to the drawings. However, the present invention is not limitedthereto.

First Embodiment

FIG. 1 shows a schematic arrangement illustrating an exposure apparatusEX according to a first embodiment. With reference to FIG. 1, theexposure apparatus EX comprises a mask stage MST which is movable whileholding a mask M, a substrate stage PST which is movable while holding asubstrate P, an illumination optical system IL which illuminates, withan exposure light beam EL, the mask M held by the mask stage MST, aprojection optical system PL which projects an image of a pattern of themask M illuminated with the exposure light beam EL onto the substrate Pheld by the substrate stage PST, and a control unit CONT whichintegrally controls the operation of the entire exposure apparatus EX. Astorage unit MRY, which stores various pieces of information in relationto the exposure process, is connected to the control unit CONT.

The exposure apparatus EX of this embodiment is a liquid immersionexposure apparatus to which the liquid immersion method is applied inorder that the exposure wavelength is substantially shortened to improvethe resolution and to substantially widen the depth of focus. Theexposure apparatus EX is provided with a liquid immersion mechanism 1which forms a liquid immersion area LR of the liquid LQ on the substrateP. The liquid immersion mechanism 1 includes a nozzle member 70 which isprovided in the vicinity of the image plane of the projection opticalsystem PL and which has a supply port 18 for supplying the liquid LQ anda recovery port 28 for recovering the liquid LQ, a liquid supplymechanism 10 which supplies the liquid LQ to the image plane side of theprojection optical system PL via the supply port 18 provided for thenozzle member 70, and a liquid recovery mechanism 20 which recovers theliquid LQ on the image plane side of the projection optical system PLvia the recovery port 28 provided for the nozzle member 70. The nozzlemember 70 is formed in an annular form so that a first optical elementLS1, which is included in a plurality of optical elements LS1 to LS5 forconstructing the projection optical system PL and which is disposedclosest to the image plane of the projection optical system PL, issurrounded over or above the substrate P (substrate stage PST).

The first optical element LS1 of the projection optical system PL, whichis disposed closest to the image plane of the projection optical systemPL, has a concave surface portion 2 which makes contact with the liquidLQ of the liquid immersion area LR. The concave surface portion 2 isprovided on the lower surface T1 of the first optical element LS1opposed to the substrate P. The exposure apparatus EX further includes aremoving unit 40 which removes any foreign matter in the space inside ofthe concave surface portion 2 of the first optical element LS1. Theremoving unit 40 includes a suction member 42 which has a suction port43 for sucking the foreign matter and which is provided on the substratestage PST that is movable on the image plane side of the projectionoptical system PL. The exposure apparatus EX further includes adetection unit 50 which detects whether or not the foreign matter ispresent in the space inside of the concave surface portion 2. Thedetection unit 50 includes an image pickup device such as CCD, which isprovided on the substrate stage PST.

The exposure apparatus EX forms the liquid immersion area LR locally ona part of the substrate P including a projection area AR of theprojection optical system PL by the liquid LQ supplied from the liquidsupply mechanism 10 at least during the period in which the patternimage of the mask M is transferred onto the substrate P, the liquidimmersion area LR being larger than the projection area AR and smallerthan the substrate P. Specifically, the exposure apparatus EX adopts thelocal liquid immersion system, wherein the optical path space, which isdisposed between the first optical element LS1 arranged closest to theimage plane of the projection optical system PL and the surface of thesubstrate P arranged on the image plane side of the projection opticalsystem PL, is filled with the liquid LQ. The liquid immersion area ofthe liquid LQ is formed on a part of the substrate P, and the exposurelight beam EL, which is allowed to pass through the mask M, is radiatedonto the substrate P via the liquid LQ and the projection optical systemPL. Accordingly, the substrate P is subjected to the projection exposurewith the pattern of the mask M. The control unit CONT locally forms theliquid immersion area LR of the liquid LQ on the substrate P such that apredetermined amount of the liquid LQ is supplied onto the substrate Pby the liquid supply mechanism 10, and a predetermined amount of theliquid LQ on the substrate P is recovered by the liquid recoverymechanism 20.

The embodiment of the present invention will be explained as exemplifiedby a case of the use of the scanning type exposure apparatus (so-calledscanning stepper) as the exposure apparatus EX in which the substrate Pis exposed with the pattern formed on the mask M while synchronouslymoving the mask M and the substrate P in mutually different directions(opposite directions) in the scanning directions. In the followingexplanation, the X axis direction resides in the synchronous movementdirection (scanning direction) for the mask M and the substrate P in thehorizontal plane, the Y axis direction (non-scanning direction) residesin the direction which is perpendicular to the X axis direction in thehorizontal plane, and the Z axis direction resides in the directionwhich is perpendicular to the X axis direction and the Y axis directionand which is coincident with the optical axis AX of the projectionoptical system PL. The directions of rotation (inclination) about the Xaxis, the Y axis, and the Z axis are designated as θX, θY, and θZdirections respectively. The term “substrate” referred to hereinincludes those obtained by coating a semiconductor wafer with a resist(photosensitive material), and the term “mask” includes a reticle formedwith a device pattern to be subjected to the reduction projection ontothe substrate.

The illumination optical system IL includes, for example, an exposurelight source, an optical integrator which uniformizes the illuminance ofthe light flux radiated from the exposure light source, a condenser lenswhich collects the exposure light beam EL supplied from the opticalintegrator, a relay lens system, and a field diaphragm which sets theillumination area on the mask M illuminated with the exposure light beamEL. The predetermined illumination area on the mask M is illuminatedwith the exposure light beam EL having a uniform illuminancedistribution by the illumination optical system IL. Those usable as theexposure light beam EL radiated from the illumination optical system ILinclude, for example, far ultraviolet light beams (DUV light beams) suchas emission lines (g-ray, h-ray, i-ray) radiated, for example, from amercury lamp, the KrF excimer laser beam (wavelength: 248 nm), and thelike, and vacuum ultraviolet light beams (VUV light beams) such as theArF excimer laser beam (wavelength: 193 nm), the F₂ laser beam(wavelength: 157 nm), and the like. In this embodiment, the ArF excimerlaser beam is used.

The mask stage MST is movable while holding the mask M. The mask stageMST holds the mask M by means of the vacuum attraction (or theelectrostatic attraction). The mask stage MST is two-dimensionallymovable in the plane perpendicular to the optical axis AX of theprojection optical system PL, i.e., in the XY plane, and it is finelyrotatable in the θZ direction in a state in which the mask M is held, inaccordance with the driving of a mask stage-driving unit MSTD includinga linear motor controlled by the control unit CONT. A movement mirror81, which is movable together with the mask stage MST, is provided onthe mask stage MST. A laser interferometer 82 is provided at a positionopposed to the movement mirror 81. The position in the two-dimensionaldirection and the angle of rotation in the θZ direction (including theangles of rotation in the θX and θY directions in some situations) ofthe mask M on the mask stage MST are measured in real-time by the laserinterferometer 82. The result of the measurement of the laserinterferometer 82 is outputted to the control unit CONT. The controlunit CONT drives the mask stage-driving unit MSTD on the basis of theresult of the measurement obtained by the laser interferometer 82 tothereby control the position of the mask M held on the mask stage MST.

The projection optical system PL projects the pattern of the mask M ontothe substrate P at a predetermined projection magnification β to performthe exposure. The projection optical system PL comprises a plurality ofoptical elements LS1 to LS5. The optical elements LS1 to LS5 aresupported by a barrel PK. In this embodiment, the projection opticalsystem PL is the reduction system having the projection magnification βwhich is, for example, ¼, ⅕, or ⅛. The projection optical system PL maybe any one of the 1× magnification system and the magnifying system. Theprojection optical system PL is the dioptric system including nocatoptric element. However, the projection optical system PL may be thecatadioptric system including dioptric and catoptric elements.

The projection optical system PL is provided with an image formationcharacteristic-adjusting unit LC as disclosed, for example, in JapanesePatent Application Laid-open Nos. 60-78454 and 11-195602. The imageformation characteristic-adjusting unit LC is adjustable of the imageformation characteristic such as the image plane position of theprojection optical system PL by driving a specified optical element ofthe plurality of optical elements LS1 to LS5 included in the projectionoptical system PL and/or adjusting the pressure in the barrel PK.

The substrate stage PST has a substrate holder PH which holds thesubstrate P. The substrate holder PH is movable on the image plane sideof the projection optical system PL. The substrate holder PH holds thesubstrate P, for example, by the vacuum attraction. A recess 86 isprovided on the substrate stage PST. The substrate holder PH for holdingthe substrate P is arranged in the recess 86. The upper surface 87 ofthe substrate stage PST other than the recess 86 is a flat surface (flatsection) which has approximately the same height as that of (flush with)the surface of the substrate P held by the substrate holder PH.

The substrate stage PST is two-dimensionally movable in the XY plane onthe base member BP, and it is finely rotatable in the θZ direction in astate in which the substrate P is held by the aid of the substrateholder PH, in accordance with the driving of the substrate stage-drivingunit PSTD including a linear motor or the like controlled by the controlunit CONT. Further, the substrate stage PST is also movable in the Zaxis direction, the θX direction, and the θY direction. Therefore, thesurface of the substrate P supported by the substrate stage PST ismovable in the directions of six degrees of freedom in the X axis, Yaxis, Z axis, θX, θY, and θZ directions. A movement mirror 83, which ismovable together with the substrate stage PST, is fixed to the sidesurface of the substrate stage PST. A laser interferometer 84 isprovided at a position opposed to the movement mirror 83. The positionin the two-dimensional direction and the angle of rotation of thesubstrate P on the substrate stage PST are measured in real time by thelaser interferometer 84. The exposure apparatus EX is provided with afocus/leveling-detecting system (not shown) based on the obliqueincidence system which detects the surface position information aboutthe surface of the substrate P held by the substrate stage PST asdisclosed, for example, in Japanese Patent Application Laid-open No.8-37149. The focus/leveling-detecting system detects the surfaceposition information about the surface of the substrate P (positioninformation in the Z axis direction, and the information about theinclination in the θX and θY directions of the substrate P). A systembased on an electrostatic capacity type sensor may be adopted for thefocus/leveling-detecting system. The result of the measurement performedby the laser interferometer 84 is outputted to the control unit CONT.The result of the detection performed by the focus/leveling-detectingsystem is also outputted to the control unit CONT. The control unit CONTdrives the substrate stage-driving unit PSTD on the basis of thedetection result of the focus/leveling-detecting system to adjust andmatch the surface of the substrate P with respect to the image plane ofthe projection optical system PL by controlling the focus position (Zposition) and the angle of inclination (θX, θY) of the substrate P.Further, the position is controlled in the X axis direction, the Y axisdirection, and the θZ direction of the substrate P on the basis of themeasurement result of the laser interferometer 84.

Next, an explanation will be made about the liquid LQ for filling theoptical path space for the exposure light beam EL therewith. In thefollowing explanation, the refractive index of the liquid LQ and therefractive index of the first optical element LS1 with respect to theexposure light beam EL (ArF laser beam, wavelength: 193 nm) will besimply referred to as “refractive index”. In this embodiment, the liquidsupply mechanism 10 supplies the liquid LQ having the refractive indexhigher than the refractive index of the first optical element LS1 whichis disposed closest to the image plane of the projection optical systemPL and which is included in the plurality of optical elements LS1 to LS5for constructing the projection optical system PL. The optical pathspace, which is disposed between the first optical element LS1 and thesubstrate P (or the substrate stage PST) arranged on the image planeside of the projection optical system PL, is filled with the liquid LQhaving the high refractive index. In this embodiment, the first opticalelement LS1 is formed of silica glass. The refractive index of theliquid LQ is higher than the refractive index of silica glass. In thiscase, the refractive index of silica glass is about 1.5, and therefractive index of the liquid LQ supplied from the liquid supplymechanism 10 is about 1.6. The first optical element LS1 may be formedof calcium fluoride.

The ArF excimer laser beam as the exposure light beam EL is transmissivethrough silica glass which is the material for forming the first opticalelement LS1. Silica glass is the material having the large refractiveindex. Therefore, for example, it is possible to decrease the size(diameter) of the first optical element LS1. It is possible to realizecompact sizes of the entire projection optical system PL and the entireexposure apparatus EX. For example, the optical elements LS2 to LS5 maybe formed of calcium fluoride, and the optical element LS1 may be formedof silica glass. Alternatively, the optical elements LS2 to LS5 may beformed of silica glass, and the optical element LS1 may be formed ofcalcium fluoride. Further alternatively, all of the optical elements LS1to LS5 may be formed of silica glass (or calcium fluoride).

FIG. 2 shows a magnified sectional view illustrating those disposed inthe vicinity of the first optical element LS1 arranged closest to theimage plane of the projection optical system PL. With reference to FIG.2, the concave surface portion 2 is formed at the lower surface T1 ofthe first optical element LS1 opposed to the substrate P. The supplyport 18 is provided on the lower surface 70A of the nozzle member 70opposed to the substrate P so that the supply port 18 surrounds theprojection area AR of the projection optical system PL. The recoveryport 28 is provided outside the supply port 18 with respect to theprojection area AR on the lower surface 70A of the nozzle member 70. Therecovery port 28 is formed to have an annular slit-shaped form on thelower surface 70A of the nozzle member 70. The space among the lowersurface T1 of the first optical element LS1, the lower surface 70A ofthe nozzle member 70, and the substrate P is filled with the liquid LQof the liquid immersion area LR.

The optical path space, which is disposed on the side of the uppersurface T2 of the first optical element LS1, is filled with the gas(nitrogen). The optical path space, which is disposed on the side of thelower surface T1 of the first optical element LS1, is filled with theliquid LQ. The upper surface T2 of the first optical element LS1 has ashape of convex curved surface to expand toward the object plane of theprojection optical system PL (toward the mask). With this shape, allbeams, which form the image on the surface of the substrate P (imageplane), are allowed to come thereinto.

The lower surface T1 of the first optical element LS1 has the concavesurface portion 2 which is recessed to make separation from thesubstrate P. The concave surface portion 2 has a curved shape. In thesame manner as the shape of the upper surface T2, the lower surface T1has such a shape that all beams, which form the image on the surface ofthe substrate P, are allowed to come thereinto.

With reference to FIG. 2, the lower surface T1 and the upper surface T2of the first optical element LS1 are depicted to have spherical shapeshaving the same center of curvature. However, the respective curvaturesand the curved shapes can be appropriately determined so that theprojection optical system PL successfully obtains the desiredperformance. It is also allowable to provide any non-spherical shape.When the lower surface T1 and the upper surface T2 have the curvedshapes including the spherical shapes, the curvatures of the lowersurface T1 and the upper surface T2 can be appropriately determined sothat all of the beams, which form the image on the surface of thesubstrate P, are allowed to come into the surfaces, and the angles ofincidence of the light beams allowed to come into the lower surface T1and the upper surface T2 are reduced in accordance with the followingprinciple.

The numerical aperture NA of the projection optical system PL on theimage plane side is represented by the following expression.NA=n·sin θ  (1)

In this expression, n represents the refractive index of the liquid LQ,and θ represents the convergence half angle. The resolution R and thedepth of focus δ are represented by the following expressionsrespectively.R=k ₁ ·λ/NA  (2)δ=±k ₂ ·λ/NA ²  (3)

In these expressions, λ represents the exposure wavelength, and k₁ andk₂ represent the process coefficients. As described above, when thenumerical aperture NA is increased about n times by the liquid LQ havingthe high refractive index (n), it is possible to greatly improve theresolution and the depth of focus according to the expressions (2) and(3).

When it is intended to obtain the numerical aperture NA of theprojection optical system PL which is not less than the refractive indexof the first optical element LS1, if the lower surface T1 is a flatsurface which is substantially perpendicular to the optical axis AX,then a part of the exposure light beam EL, which includes the outermostbeam K of the exposure light beam EL, is totally reflected by theinterface between the first optical element LS1 and the liquid LQ, andthe part of the exposure light beam EL cannot arrive at the image planeof the projection optical system PL. For example, the followingexpression holds according to the Snell's law provided that n₁represents the refractive index of the first optical element LS1, n₂represents the refractive index of the liquid LQ, θ₁ represents theangle of the outermost beam K of the exposure light beam EL allowed tocome into the interface (lower surface T1) between the first opticalelement LS1 and the liquid LQ with respect to the optical axis AX, andθ₂ represents the angle of the beam K allowed to outgo from theinterface (allowed to come into the liquid LQ) with respect to theoptical axis AX.n₁ sin θ₁=n₂ sin θ₂  (4)

The numerical aperture of the projection optical system PL isrepresented by the following expression by the refractive index n₂ ofthe liquid LQ and the angle θ₂ of the beam K allowed to come into theliquid LQ with respect to the optical axis AX.NA=n₂sin θ₂  (5)

According to the expressions (4) and (5), the following expressionholds.sin θ₁ =NA/n ₁  (6)

Therefore, as clarified from the expression (6) as well, if theinterface (lower surface T1) between the first optical element LS1 andthe liquid LQ is the flat surface substantially perpendicular to theoptical axis AX, and the numerical aperture NA of the projection opticalsystem PL is larger than the refractive index n₁ of the first opticalelement LS1, then the part of the light beam, which includes theoutermost beam K of the exposure light beam EL, cannot come into theliquid LQ. On the contrary, the lower surface T1 of the first opticalelement LS1 of this embodiment has the concave surface portion 2.Therefore, it is possible to lower the angle of incidence of the lightbeam allowed to come into the interface (lower surface T1) between thefirst optical element LS1 and the liquid LQ, especially the beaminclined with respect to the optical axis AX of the projection opticalsystem PL. Accordingly, even when the numerical aperture NA of theprojection optical system PL is larger than the refractive index n₁ ofthe first optical element LS1, the outmost beam K of the exposure lightbeam EL can arrive at the image plane satisfactorily without beingtotally reflected by the interface.

Next, an explanation will be made about the liquid supply mechanism 10and the liquid recovery mechanism 20 of the liquid immersion mechanism1. FIG. 3 shows parts of the liquid supply mechanism 10. As shown inFIGS. 1 and 3, the liquid supply mechanism 10 of this embodiment isprovided with a first liquid supply section 11 which is capable offeeding a first liquid LQ1, a second liquid supply section 12 which iscapable of feeding a second liquid LQ2, and a mixing unit 19 which mixesthe first liquid LQ1 fed from the first liquid supply section 11 and thesecond liquid LQ2 fed from the second liquid supply section 12. Theliquid LQ, which is prepared by the mixing unit 19, is supplied to theimage plane side of the projection optical system PL. The first liquidLQ1 and the second liquid LQ2 are different from each other. The mixingunit 19 mixes the two types of the liquids LQ1, LQ2. As described above,the exposure apparatus of this embodiment is provided with the mixingunit which mixes the two types of the liquids LQ1, LQ2. Accordingly, itis possible to appropriately adjust the optical properties such as thetransmittance and the refractive index of the liquid LQ for forming theliquid immersion area LR. In this embodiment, glycerol, which has arefractive index of about 1.61, is used as the first liquid LQ1, andisopropanol, which has a refractive index of about 1.50, is used as thesecond liquid LQ2. The amounts of the first liquid LQ1 and the secondliquid LQ2 are adjusted so that the liquid LQ, which is obtained bymixing them, has a refractive index of about 1.60.

Each of the first and second liquid supply sections 11, 12 includes, forexample, a tank for accommodating the first or second liquid LQ1, LQ2, apressurizing pump, a temperature-adjusting unit for adjusting thetemperature of the first or second liquid LQ1, LQ2 to be supplied, afilter unit for removing any foreign matter (including any bubble) fromthe first or second liquid LQ1, LQ2, and the like. It is not necessarythat the exposure apparatus EX is provided with all of the tank, thepressurizing pump, the filter unit and the like of the liquid supplymechanism 10. These components may be replaced with the equipment of afactory or the like in which the exposure apparatus EX is installed. Oneend of a first supply tube 13 is connected to the first liquid supplysection 11. The other end of the first supply tube 13 is connected to acollective tube 15. One end of a second supply tube 14 is connected tothe second liquid supply section 12. The other end of the second supplytube 14 is connected to the collective tube 15. The first liquid LQ1,which is fed from the first liquid supply section 11, is allowed to flowthrough the first supply tube 13, and then the first liquid LQ1 issupplied to the mixing unit 19 via the collective tube 15. The secondliquid LQ2, which is fed from the second liquid supply section 12, isallowed to flow through the second supply tube 14, and then the secondliquid LQ2 is supplied to the mixing unit 19 via the collective tube 15.

Valves 13B, 14B are provided for the first and second supply tubes 13,14 respectively. The operations of the valves 13B, 14B are controlled bythe control unit CONT. The control unit CONT adjusts the valves 13B, 14B(opening degrees of the valves 13B, 14B), and thus the supply amountsper unit time of the first and second liquids LQ1, LQ2, which aresupplied from the first and second liquid supply sections 11, 12 to themixing unit 19 via the first and second supply tubes 13, 14 and thecollective tube 15, are adjusted respectively.

The liquid LQ, which is returned from the liquid recovery mechanism 20,can be also supplied to the mixing unit 19. The liquid LQ, which isreturned from the liquid recovery mechanism 20, is supplied to themixing unit 19 via a return tube 27. The mixing unit 19 mixes the firstand second liquids LQ1, LQ2 supplied from the first and second liquidsupply sections 11, 12 via the first and second supply tubes 13, 14 andthe collective tube 15 with the liquid LQ supplied from the liquidrecovery mechanism 20 via the return tube 27. One end of a supply tube16 is connected to the mixing unit 19, and the other end is connected tothe nozzle member 70. A supply internal flow passage, which has one endconnected to the supply port 18, is formed in the nozzle member 70. Theother end of the supply tube 16 is connected to the other end of thesupply internal flow passage. The liquid LQ, which is prepared orproduced by the mixing unit 19, is supplied to the nozzle member 70 viathe supply tube 16. The liquid LQ is allowed to flow through the supplyinternal flow passage of the nozzle member 70, and then the liquid LQ issupplied from the supply port 18 to the image plane side of theprojection optical system PL.

With reference to FIG. 1, the liquid recovery mechanism 20 includes aliquid recovery section 21 which is capable of recovering the liquid LQin order to recover the liquid LQ on the image plane side of theprojection optical system PL, and a recovery tube 26 which has one endconnected to the liquid recovery section 21. The other end of therecovery tube 26 is connected to the nozzle member 70. The liquidrecovery section 21 is provided with, for example, a vacuum system(suction unit) such as a vacuum pump or the like, a gas/liquid separatorfor separating the recovered liquid LQ from the gas, and a tank foraccommodating the recovered liquid LQ. It is not necessary that theexposure apparatus EX is provided with all of the vacuum system, thegas/liquid separator, the tank and the like of the liquid recoverymechanism 20. These components may be replaced with the equipment of afactory or the like in which the exposure apparatus EX is installed. Arecovery internal flow passage, which has one end connected to therecovery port 28, is formed in the nozzle member 70. The other end ofthe recovery tube 26 is connected to the other end of the recoveryinternal flow passage of the nozzle member 70. When the vacuum system ofthe liquid recovery section 21 is driven, then the liquid LQ on thesubstrate P, which is arranged on the image plane side of the projectionoptical system PL, is allowed to flow into the recovery internal flowpassage from the recovery port 28, and the liquid LQ is recovered by theliquid recovery section 21 via the recovery tube 26.

The liquid recovery mechanism 20 is provided with a process unit 60which applies a predetermined treatment to the recovered liquid LQ. Theliquid recovery mechanism 20 returns the liquid LQ after being processedwith the process unit 60 to the mixing unit 19 of the liquid supplymechanism 10 via the return tube 27. The process unit 60 cleans therecovered liquid LQ, which includes, for example, a filter unit and adistillation unit. The liquid LQ, which is recovered by the liquidrecovery mechanism 20, may possibly contain any impurity generated fromthe substrate P due to the contact with the substrate P coated with theresist. Accordingly, the liquid recovery mechanism 20 cleans a part ofthe recovered liquid LQ with the process unit 60, and then the cleanedliquid LQ is returned to the mixing unit 19 of the liquid supplymechanism 10. A part of the residual of the recovered liquid LQ isdischarged (discarded) by the liquid recovery mechanism 20 to theoutside of the exposure apparatus EX without returning the part of theresidual of the recovered liquid LQ to the liquid supply mechanism 10.

The liquid supply mechanism 10 further includes a measuring unit 30which measures the optical property of the liquid LQ to be supplied tothe image plane side of the projection optical system PL. The measuringunit 30 includes a first measuring unit 31 which is provided at anintermediate position of the return tube 27 disposed between the mixingunit 19 and the process unit 60 of the liquid recovery mechanism 20, anda second measuring unit 32 which is provided at an intermediate positionof the supply tube 16 disposed between the mixing unit 19 and the nozzlemember 70. The first measuring unit 31 measures the optical property ofthe liquid LQ which is returned from the process unit 60 of the liquidrecovery mechanism 20 before being supplied to the mixing unit 19. Thesecond measuring unit 32 measures the optical property of the liquid LQwhich is prepared by the mixing unit 19 before being supplied to theimage plane side of the projection optical system PL via the nozzlemember 70. The first measuring unit 31 and the second measuring unit 32are constructed substantially equivalently, which can measure at leastone of the refractive index of the liquid LQ and the transmittance ofthe liquid LQ.

The control unit CONT adjusts the first and second valves 13B, 14Bprovided for the first and second supply tubes 13, 14 on the basis ofthe measurement result of the first measuring unit 31 to adjust thesupply amounts per unit time of the first and second liquids LQ1, LQ2 tobe supplied from the first and second liquid supply sections 11, 12 tothe mixing unit 19 respectively. In other words, the control unit CONTadjusts the mixing ratio of the first and second liquids LQ1, LQ2supplied from the first and second liquid supply sections 11, 12respectively and mixed in the mixing unit 19 on the basis of themeasurement result of the first measuring unit 31. In this embodiment,the mixing ratio of the first liquid LQ1 and the second liquid LQ2 isadjusted so that the refractive index is approximately 1.60.

The first and second liquids LQ1, LQ2 are the liquids of the differenttypes. Therefore, the optical properties (refractive index, lighttransmittance) may be highly possibly different from each other.Accordingly, in order to obtain the desired state of the opticalproperty of the liquid LQ to be prepared by the mixing unit 19,specifically in order to maintain a predetermined value of at least oneof the refractive index and the light transmittance of the liquid LQprepared by the mixing unit 19, the control unit CONT adjusts the mixingratio of the first and second liquids LQ1, LQ2 subjected to the mixingin the mixing unit 19 on the basis of the measurement result of thefirst measuring unit 31. The first measuring unit 31 measures theoptical property of the liquid LQ returned from the liquid recoverymechanism 20. Therefore, the control unit CONT can maintain the desiredstate of the optical property of the liquid LQ prepared by the mixingunit 19 such that appropriate amounts of the first and second liquidsLQ1, LQ2 are appropriately added to the returned liquid LQ from thefirst and second liquid supply sections 11, 12 on the basis of themeasurement result of the first measuring unit 31. As described above,each of the first and second liquid supply sections 11, 12 is providedwith the temperature-adjusting unit for maintaining the constanttemperature of each of the first and second liquids LQ1, LQ2. Therefore,the control unit CONT avoids the fluctuation of the optical property ofthe liquid LQ which would be otherwise caused by the fluctuation of thetemperature of the liquid LQ, by controlling the temperature-adjustingunit.

The relationship between the mixing ratio of the first and secondliquids LQ1, LQ2 and the optical property of the liquid LQ prepared onthe basis of the mixing ratio is previously determined, for example, byan experiment or simulation. The information about the relationship ispreviously stored in the storage unit MRY connected to the control unitCONT. The control unit CONT can adjust the first and second valves 13B,14B on the basis of the information stored in the storage unit MRY andthe measurement result obtained by the first measuring unit 31 todetermine the mixing ratio of the first and second liquids LQ1, LQ2 inorder to obtain the desired optical property of the liquid LQ.

The optical property of the liquid LQ prepared by the mixing unit 19 ismeasured by the second measuring unit 32. The control unit CONT adjusts,for example, the positional relationship between the surface of thesubstrate P and the position of the image plane formed via theprojection optical system PL and the liquid LQ on the basis of themeasurement result of the second measuring unit 32. Specifically, thecontrol unit CONT uses the image formation characteristic-adjusting unitLC provided for the projection optical system PL on the basis of themeasurement result of the second measuring unit 32 so that the specifiedoptical element of the plurality of optical elements LS1 to LS5 forconstructing the projection optical system PL is driven and/or thepressure in the barrel PK is adjusted to adjust the position of theimage plane of the projection optical system PL thereby. Accordingly,even when, for example, the refractive index, which is included in theoptical property of the liquid LQ prepared by the mixing unit 19, isslightly varied, and the image plane position via the projection opticalsystem PL and the liquid LQ is varied, then the image formationcharacteristic is adjusted in response to the optical property(refractive index) of the liquid LQ, and thus the surface of thesubstrate P can be aligned with the position of the image plane formedvia the projection optical system PL and the liquid LQ. The control unitCONT may be operated such that the surface position of the substrate Pis adjusted by driving the substrate stage PST, the mask stage MST,which holds the mask M, is driven, and/or the temperature of the liquidLQ to be supplied is adjusted, in place of the adjustment of theprojection optical system PL by the image formationcharacteristic-adjusting unit LC or in combination with the adjustmentby the image formation characteristic-adjusting unit LC. In this case,the relationship between the optical property of the liquid LQ and theposition of the image plane formed via the projection optical system PLand the liquid LQ is previously determined, for example, by anexperiment or simulation, and the information about the relationship ispreviously stored in the storage unit MRY connected to the control unitCONT. The control unit CONT can use, for example, the image formationcharacteristic-adjusting unit LC on the basis of the information storedin the storage unit MRY and the measurement result of the secondmeasuring unit 32 so that the surface of the substrate P is consistentor coincident with the position of the image plane formed via theprojection optical system PL and the liquid LQ. When the lighttransmittance, which is included in the optical property of the liquidLQ, is varied, the control unit CONT adjusts, for example, theillumination optical system IL including the light source on the basisof the measurement result of the second measuring unit 32, and theexposure amount control parameter can be adjusted in the scanningexposure including, for example, the scanning velocity of the substrateP and the radiation amount (illuminance) of the exposure light beam EL.

Next, the removing unit 40 will be explained. FIG. 4 shows the removingunit 40. As shown in FIGS. 1 and 4, the exposure apparatus EX isprovided with the removing unit 40 which removes the foreign matter inthe space inside of the concave surface portion 2 of the first opticalelement LS1. The removing unit 40 includes the suction member 42 whichhas the suction port 43 for sucking the foreign matter and which isprovided for the substrate stage PST. As shown in FIG. 4, the removingunit 40 includes the suction member 42 which is arranged inside a hole45 formed at a part of the upper surface 87 of the substrate stage PST,and a driving mechanism 44 which drives the suction member 42. Thesuction member 42 is a pipe-shaped member, and its upper end (one end)is the suction port 43. The suction port 43 is provided on the uppersurface 87 of the substrate stage PST. The suction port 43 is arrangedoutside the exposure light beam EL during the exposure for the substrateP. The suction member 42 is movable in the Z axis direction inaccordance with the driving force of the driving mechanism 44. Thesuction port 43 appears and disappears with respect to the upper surface87 of the substrate stage PST. In this embodiment, when the suctionmember 42 is moved downwardly and arranged inside the hole 45, thesuction port 43, which is provided at the upper end of the suctionmember 42, is substantially flush with the upper surface 87 of thesubstrate stage PST as shown in FIG. 4. The suction member 42 may bemovable in the oblique direction in relation to the Z axis direction.

The suction port 43, which is provided on the upper surface 87 of thesubstrate stage PST, can be opposed to the concave surface portion 2 onthe lower surface T1 of the first optical element LS1 of the projectionoptical system PL in accordance with the movement of the substrate stagePST. On the other hand, the lower end (the other end) of the suctionmember 42 is connected to the suction unit 41 via a flow passage-formingmember 46. The suction unit 41 includes, for example, a vacuum systemsuch as a vacuum pump, which is capable of sucking and recovering theliquid. A part of the flow passage-forming member 46 has anexpandable/contractible portion 47 which is expandable/contractible inorder not to inhibit the movement of the suction member 42.

Next, an explanation will be made with reference to a flow chart shownin FIG. 12 about the operation for exposing the substrate P by theexposure apparatus EX constructed as described above. When the substrateP is subjected to the exposure, the control unit CONT starts theoperation for forming the liquid immersion area LR of the liquid LQ bythe liquid immersion mechanism 1. It is assumed that the substrate P tobe subjected to the exposure process is already loaded on the substrateholder PH. When the operation for forming the liquid immersion area LRis started, the control unit CONT moves the substrate stage PST so thatthe concave surface portion 2 of the first optical element LS1 of theprojection optical system PL is opposed to the recovery port 43 of theremoving unit 40. The control unit CONT starts the supply operation ofthe liquid LQ by the liquid supply mechanism 10 of the liquid immersionmechanism 1 and the recovery operation of the liquid LQ by the liquidrecovery mechanism 20 in the state in which the concave surface portion2 of the first optical element LS1 of the projection optical system PLis opposed to the recovery port 43 of the removing unit 40 (S1).

FIG. 5 shows a state which is brought about immediately after startingthe operation for forming the liquid immersion area LR. As shown in FIG.5, when the operation for forming the liquid immersion area LR isstarted, there is such a possibility that any bubble (gas portion) maybe formed in the liquid LQ. There is such a possibility that the bubblemay be also formed after the elapse of a predetermined period of timeafter the start of the operation for forming the liquid immersion areaLR depending on the state of the liquid immersion mechanism 1. In thisembodiment, the first optical element LS1 has the concave surfaceportion 2. Therefore, there is such a high possibility that the bubble,which has a specific gravity smaller than that of the liquid LQ, staysat the highest position of the concave surface portion 2 or in thevicinity thereof. The control unit CONT drives the driving mechanism 44of the removing unit 40 to move the suction member 42 upwardly so thatthe suction port 43, which is provided at the upper end of the suctionmember 42, is moved in the +Z direction, and the substrate stage PST, onwhich the suction member 42 is provided, is moved in the XY directionsby the aid of the substrate stage-driving unit PSTD. Accordingly, thecontrol unit CONT moves the suction port 43 relatively with respect tothe concave surface portion 2 by the driving mechanism 44 and thesubstrate stage-driving unit PSTD to arrange the suction port 43 at theposition optimum for the concave surface portion 2. Specifically, thecontrol unit CONT arranges the suction port 43 of the removing unit 44at the position in the vicinity of the position at which the bubble isarranged, i.e., at the highest position of the concave surface portion 2or in the vicinity thereof, by the driving mechanism 44 and thesubstrate stage-driving unit PSTD. The control unit CONT drives thesuction unit 41 in a state in which the suction port 43 is allowed toapproach the concave surface portion 2 while leaving a predetermineddistance (for example, about 1 mm) to suck and remove the bubble havingthe specific gravity smaller than that of the liquid LQ by the aid ofthe suction port 43, the bubble being contained in the liquid LQ in thespace inside of the concave surface portion 2 (S2). In this procedure,the liquid supply operation by the liquid supply mechanism 10 of theliquid immersion mechanism 1 and the liquid recovery operation by theliquid recovery mechanism 20 are continued even when the operation toremove the bubble is performed by the removing unit 40. The suctionamount and the relative distance between the suction port 43 and theconcave surface portion 2, which are provided when the suction-port 43sucks the bubble, are optimally adjusted depending on the physicalproperties such as the viscosity of the liquid LQ to be used. Thesuction operation (removal operation) may be executed while moving thesuction port 43 in the Z direction (+Z direction and/or −Z direction).Alternatively, the suction operation (removal operation) may be executedwhile moving the suction port 43 in the direction perpendicular to the Zaxis so that the suction port 43 does not collide with the concavesurface portion 2.

The removing unit 40 can suck and remove any foreign matter having aspecific gravity smaller than that of the liquid LQ in the liquid LQ inthe space inside of the concave surface portion 2 without being limitedto the bubble contained in the liquid LQ.

In this procedure, the operation for forming the liquid immersion areaLR is started by the liquid immersion mechanism 1 in the state in whichthe suction port 43 is opposed to the concave surface portion 2.However, the following procedure is also available. That is, the liquidimmersion area LR is formed in an area (including the surface of thesubstrate P) of the upper surface 87 of the substrate stage PST, thearea being away from an area in which the suction port 43 is provided.After that, the substrate stage PST is moved in the XY directions sothat the suction port 43 is opposed to the concave surface portion 2 ofthe first optical element LS1. The foreign matter in the space inside ofthe concave surface portion 2 can be also removed smoothly such that theconcave surface portion 2 is opposed to the suction port 43, and thenthe suction port 43 is allowed to approach the concave surface portion 2to start the suction operation.

After the operation for removing the bubble contained in the liquid LQis completed, the control unit CONT moves the suction member 42 of theremoving unit 40 downwardly so that the suction member 42 is arrangedinside the hole 45. The control unit CONT confirms, by the detectionunit 50, whether or not the bubble (foreign matter) is removed from theliquid LQ in the space inside of the concave surface portion 2. That is,the control unit CONT moves the substrate stage PST in the XY directionsso that the liquid immersion area LR, which is formed on the uppersurface 87 of the substrate stage PST, is moved to the position over orabove the detection unit 50. In this procedure, the liquid supplyoperation by the liquid supply mechanism 10 of the liquid immersionmechanism 1 and the liquid recovery operation by the liquid recoverymechanism 20 are also continued during the period in which the substratestage PST is moved in the XY directions.

FIG. 6 shows a state in which the detection unit 50 detects the foreignmatter (including the bubble). With reference to FIG. 6, the detectionunit 50 is provided at the inside of the substrate stage PST. Thedetection unit 50 is arranged in the internal space 56 of the substratestage PST. The detection unit 50 includes an optical system 51 which isarranged under a transparent member 54, and an image pickup element 53which is composed of, for example, CCD. The image pickup element 53 iscapable of obtaining an optical image (image) of, for example, theliquid LQ and the first optical element LS1 via the transparent member54 and the optical system 51. The image pickup element 53 coverts theobtained image into an electric signal, and the signal (imageinformation) is outputted to the control unit CONT. The detection unit50 further includes an adjusting mechanism 52 which is capable ofadjusting the focus position of the optical system 51. The detectionunit 50 has a field capable of observing the entire liquid LQ arrangedinside the concave surface portion 2. The entire detection unit 50 maybe arranged in the substrate stage PST. Alternatively, for example, apart of the optical element among a plurality of optical elements forconstructing the optical system 51 and the image pickup element 53, andthe like may be arranged outside the substrate stage PST. Anotherarrangement may be also adopted, in which the adjusting mechanism 52 isomitted.

The control unit CONT uses the detection unit 50 to detect whether ornot any bubble (foreign matter) is present in the liquid LQ of theliquid immersion area LR formed on the transparent member 54 (S3). Thedetection unit 50 observes, through the transparent member 54, theliquid LQ of the liquid immersion area LR on the upper surface of thetransparent member 54. When the detection unit 50 observes the state ofthe liquid immersion area LR, the substrate stage PST substantiallystands still. The image pickup element 53 of the detection unit 50obtains the image of the liquid LQ for forming the liquid immersion areaLR on the transparent member 54, via the transparent member 54 and theoptical system 51. When the bubble (foreign matter) in the space insideof the concave surface portion 2, is detected by the detection unit 50,the control unit CONT uses the adjusting mechanism 52 to adjust thefocus position of the optical system 51 to the position in the vicinityof the concave surface portion 2. Therefore, the image pickup element 53can satisfactorily obtain the image of the liquid LQ in the concavesurface portion 2 disposed over or above the transparent member 54. Thedetection unit 50 has the field which is larger than the concave surfaceportion 2. Therefore, it is possible to collectively obtain the fullfield image of the liquid LQ in the space inside of the concave surfaceportion 2.

The image information obtained by the image pickup element 53 isoutputted to the control unit CONT. The control unit CONT performs thecalculation processing (image processing) for the signal (imageinformation) outputted from the image pickup element 53 to judge whetheror not the bubble (foreign matter) is present in the liquid LQ on thebasis of the result of the processing (S4).

If it is judged or determined that the bubble (foreign matter) is absentin the liquid LQ on the basis of the detection result of the detectionunit 50, the control unit CONT performs the measurement process byvarious measuring units (not shown) provided on the substrate stage PST(S5). That is, the control unit CONT moves the substrate stage PST inthe XY directions to move the liquid immersion area LR onto themeasuring unit from the position on the transparent member 54. Themeasuring unit as described above is provided to perform the measurementprocess in relation to the exposure process. The measuring unit includesa substrate alignment system based on the FIA (field image alignment)system as disclosed, for example, in Japanese Patent ApplicationLaid-open No. 4-65603 and a reference member having any mark to bemeasured by a mask alignment system based on the VRA (visual reticlealignment) as disclosed, for example, in Japanese Patent ApplicationLaid-open No. 7-176468. The measuring unit further includes, forexample, unevenness sensors for measuring the uneven illuminance asdisclosed in Japanese Patent Application Laid-open No. 57-117238 and formeasuring the fluctuation amount of the transmittance of the exposurelight beam EL of the projection optical system PL as disclosed inJapanese Patent Application Laid-open No. 2001-267239, a spatialimage-measuring sensor as disclosed in Japanese Patent ApplicationLaid-open No. 2002-14005, and a radiation amount sensor (illuminancesensor) as disclosed in Japanese Patent Application Laid-open No.11-16816. The measurement process is performed in a state in which theliquid immersion area LR of the liquid LQ is arranged on a predeterminedmeasuring unit of the respective measuring units as described above. Thebaseline amount is derived and the calibration process for theprojection optical system PL is performed by the control unit CONT onthe basis of the measurement result obtained thereby. The referencemember and the sensor, which are to be used for the measurement processas described above, will be briefly explained in a third embodimentdescribed later on.

After the completion of, for example, the calibration process for theprojection optical system PL, the control unit CONT moves the substratestage PST in the XY directions so that the liquid immersion area LR,which is formed on the upper surface 87 of the substrate stage PST, ismoved onto the substrate P. The control unit CONT radiates the exposurelight beam EL onto the substrate P via the projection optical system PLand the liquid LQ from which the bubble (foreign matter) is removed toexpose the substrate P (S6).

On the other hand, if it is judged that the bubble (foreign matter) ispresent in the liquid LQ (YES in S4) on the basis of the detectionresult of the detection unit 50, then the control unit CONT moves thesubstrate stage PST in the XY directions, and the liquid immersion areaLR is moved again from the position on the transparent member 54 to theposition over or above the recovery port 43 of the removing unit 40. Thecontrol unit CONT performs the operation for removing the bubble(foreign matter) by the removing unit 40 (S1). After performing theoperation for removing the bubble (foreign matter) by the removing unit40, the control unit CONT uses the detection unit 50 again to detectwhether or not the bubble (foreign matter) is present in the liquid LQ(S2). The operation as described above is repeated until the bubble(foreign matter) is not detected in the liquid LQ by the detection unit50. After the bubble (foreign matter) is not detected in the liquid LQ,the liquid immersion exposure is performed for the substrate P (S6).

In this procedure, after the liquid immersion area LR is formed by theliquid immersion mechanism 1, the control unit CONT uses the removingunit 40 to perform the operation for removing the bubble (foreignmatter) contained in the liquid LQ, and then the control unit CONT usesthe detection unit 50 to detect whether or not the bubble (foreignmatter) contained in the liquid LQ is removed. However, it is alsoallowable to detect whether or not the bubble (foreign matter) ispresent in the liquid LQ by the detection unit 50 without performing theoperation for removing the bubble (foreign matter) contained in theliquid LQ by the removing unit 40 after forming the liquid immersionarea LR by the liquid immersion mechanism 1. In this procedure, when itis judged that the bubble (foreign matter) is absent in the liquid LQ onthe basis of the detection result of the detection unit 50, the controlunit CONT can perform the measurement process based on the use of themeasuring unit and the exposure process for the substrate P withoutperforming the removing operation by the removing unit 40. Therefore, itis possible to omit any useless operation which would be otherwiseperformed such that the removing operation is performed by the removingunit 40 although the bubble (foreign matter) is absent in the liquid LQ.

The control unit CONT can also perform the operation for removing thebubble (foreign matter) based on the use of the removing unit 40, forexample, at every predetermined period of time or every time when apredetermined number of substrates are processed, irrelevantly to thedetection result of the detection unit 50. The operation for removingthe bubble (foreign matter) by the removing unit 40 and the detectingoperation by the detection unit 50 may be performed after the exposurefor the substrate P (before unloading the substrate P from the substrateholder PH).

As explained above, the first optical element LS1, which is included inthe plurality of optical elements LS1 to LS5 for constructing theprojection optical system PL and which is disposed closest to the imageplane of the projection optical system PL, has the concave surfaceportion 2 which makes contact with the liquid LQ. Therefore, even whenthe liquid LQ has the refractive index higher than that of the firstoptical element LS1, the exposure light beam EL is successfully allowedto arrive at the substrate P (image plane) arranged on the image planeside of the projection optical system PL satisfactorily via the firstoptical element LS1 and the liquid LQ. Even when any bubble (foreignmatter) enters the space inside of the concave surface portion 2, thebubble (foreign matter) is removed by the removing unit 40. Therefore,it is possible to allow the exposure light beam EL to satisfactorilyarrive at the substrate P (image plane) arranged on the image plane sideof the projection optical system PL.

Second Embodiment

Next, a second embodiment will be explained with reference to FIG. 7. Inthe following description, any explanation will be simplified or omittedfor constitutive parts which are the same as or equivalent to those ofthe embodiment described above. The point of the second embodimentdifferent from the first embodiment, i.e., the feature of the secondembodiment resides in the fact that a part of the removing unit 40 isprovided for a nozzle member 70′. That is, in the second embodiment, asuction port 43′ of the removing unit 40 is provided on the nozzlemember 70′. The suction port 43′ is connected to the suction unit 41 viaa flow passage 46′ formed in the nozzle member 70′. As shown in FIG. 7,a part of the nozzle member 70′ is arranged under the concave surfaceportion 2 of the first optical element LS1. An opposing surface 71,which is opposed to the concave surface portion 2, is formed by the partof the nozzle member 70′ arranged under the concave surface portion 2.The suction port 43′ is formed on the opposing surface 71.

In the projection optical system PL of this embodiment, the optical pathfor the exposure light beam EL is deviated with respect to the opticalaxis AX (Z axis). That is, an area (hereinafter referred to as“effective area”) A1 of the concave surface portion 2, through which theexposure light beam EL passes, is deviated with respect to the center ofthe concave surface portion 2 (highest position of the concave surfaceportion 2). An area (hereinafter referred to as “non-effective area”)A2, through which the exposure light beam EL does not pass, is providedin the vicinity of the highest position of the concave surface portion2. The opposing surface 71 is provided opposite to the non-effectivearea A2 of the concave surface portion 2. The suction port 43′, which isprovided on the opposing surface 71, is provided at the position opposedto the concave surface portion 2 outside the optical path for theexposure light beam EL.

The bubble (foreign matter) in the space inside of the concave surfaceportion 2, can be also removed by the aid of the suction port 43′without disturbing the passage of the exposure light beam EL byproviding the suction port 43′ at the part of the nozzle member 70′ atthe position outside the optical path for the exposure light beam ELopposite to the concave surface portion 2. In this embodiment, it isalso possible to concurrently perform the exposure operation for thesubstrate P in a state in which the optical path space for the exposurelight beam EL between the first optical element LS1 and the substrate Pis filled with the liquid LQ and the sucking operation by the removingunit 40 by the aid of the suction port 43′.

Third Embodiment

Next, a third embodiment will be explained with reference to FIGS. 8 to10. The point of the third embodiment different from the firstembodiment, i.e., the feature of the third embodiment resides in thefact that an exposure apparatus EX2 has first and second stages PST1,PST2 which are movable on the image plane side of the projection opticalsystem PL. The first stage PST1 is a substrate stage which is movablewhile holding the substrate P. The second stage PST2 is a measuringstage which carries measuring units for performing the measurementprocess in relation to the exposure process as disclosed, for example,in Japanese Patent Application Laid-open No. 11-135400. The removingunit 40 and the detection unit 50 are provided for the measuring stagePST2.

As shown in a plan view in FIG. 9, a reference member 300, which hasmarks as described above, is provided as the measuring unit on an uppersurface 88 of the measuring stage PST2. An upper plate 400 forconstructing an unevenness sensor as described above, an upper plate 500for constructing a part of a spatial image-measuring sensor, and anupper plate 600 for constructing a part of a radiation amount sensor(illuminance sensor) are provided as measuring units on the uppersurface 88. The upper surface of the reference member 300 and the uppersurfaces of the upper plates 400, 500, 600 are substantially flush withthe upper surface 88 of the measuring stage PST2 and the upper surfaceof the transparent member 54 of the detection unit 50. The measuringunits provided for the measuring stage PST2 are not limited to thosedescribed herein. It is possible to carry various measuring units, ifnecessary.

When the substrate P is exposed by the exposure apparatus EX2, thecontrol unit CONT firstly drives the liquid immersion mechanism 1 toform the liquid immersion area LR on the measuring stage PST2 in a statein which the first optical element LS1 of the projection optical systemPL is opposed to the measuring stage PST2. Subsequently, the controlunit CONT performs the operation for removing the bubble (foreignmatter) contained in the space inside of the concave surface portion 2of the first optical element LS1 by the removing unit 40 provided forthe measuring stage PST2 in the same manner as in the first embodiment.The control unit CONT confirms whether or not the bubble (foreignmatter) contained in the space inside of the concave surface portion 2is removed, by the detection unit 50. If it is judged that the bubble(foreign matter) is present in the space inside of the concave surfaceportion 2 on the basis of the detection result obtained by the detectionunit 50, the control unit CONT performs the operation for removing thebubble (foreign matter) by the removing unit 40 again. On the otherhand, if it is judged that the bubble (foreign matter) is absent in thespace inside of the concave surface portion 2 on the basis of thedetection result obtained by the detection unit 50, the control unitCONT moves the liquid immersion area LR onto the substrate stage PST1after performing the measurement process by the various measuring unitsas described above. In this procedure, the control unit CONT moves thesubstrate stage PST1 to the load position to load the substrate P to besubjected to the exposure process on the substrate stage PST1 during theperiod in which the operation for removing the bubble (foreign matter)based on the use of the removing unit 40 provided on the measuring stagePST2, the operation for detecting the bubble (foreign matter) based onthe use of the detection unit 50, or the measurement process based onthe use of the measuring unit is performed.

As shown in FIG. 10, when the liquid immersion area LR on the measuringstage PST2 is moved onto the substrate stage PST1, then the control unitCONT moves the substrate stage PST1 and the measuring stage PST2 in theXY directions together in a state in which the substrate stage PST1 andthe measuring stage PST2 are allowed to make approach closely to oneanother or make contact with each other, and the liquid immersion areaLR is moved between the upper surface 87 of the substrate stage PST1 andthe upper surface 88 of the measuring stage PST2. After the liquidimmersion area LR is moved onto the substrate stage PST1, the controlunit CONT exposes the substrate P on the substrate stage PST1 via theprojection optical system PL and the liquid LQ. The control unit CONTperforms the exposure process for the substrate P in consideration ofthe measurement result of the measurement process performed on themeasuring stage PST2.

In the first to third embodiments described above, the control unit CONTmay start the suction operation while the suction port 43 of theremoving unit 40 is moved closer to the concave surface portion 2 by apredetermined distance before the operation for forming the liquidimmersion area LR is started, i.e., in a state in which the side of thelower surface T1 of the concave surface portion 2 is not filled with theliquid LQ. The supply operation and the recovery operation for theliquid LQ by the liquid immersion mechanism 1 may be started in a statein which the suction operation is continued by the aid of the suctionport 43. Accordingly, it is possible to further suppress the formationof the bubble (gas portion). When the suction operation is started bythe aid of the suction port 43 before being filled with the liquid LQ,then the foreign matter, which floats in the gas space inside of theconcave surface portion 2, can be removed, and then the side of thelower surface T1 of the concave surface portion 2 can be filled with theliquid LQ.

In the embodiments described above, the explanation has been made asexemplified by the case in which the suction port of the removing unitis provided, for example, on the nozzle member, the movable member, andthe like (for example, the substrate stage, the measuring stage, and thelike) which is movable on the image plane side of the projection opticalsystem PL by way of example. However, for example, a suction memberhaving a suction port may be supported by a support member called“column (body)” for supporting the projection optical system PL.Alternatively, a suction port to be connected to the suction unit may beformed at a portion of the concave surface portion 2 of the firstoptical element LS1 outside the optical path for the exposure light beamEL.

In the embodiments described above, the removing unit 40 removes thebubble (foreign matter) in the concave surface portion 2 formed on thelower surface T1 of the first optical element LS1 which is disposedclosest to the image plane of the projection optical system PL and whichis included in the plurality of optical elements LS1 to LS5 forconstructing the projection optical system PL. However, a concavesurface portion, which makes contact with the liquid, may be formed onany surface other than the lower surface of the first optical elementLS1 depending on the arrangement of the projection optical system PL.Alternatively, a concave surface portion, which makes contact with theliquid, may be formed on any one of the optical elements LS2 to LS5other than the first optical element LS1. For example, the liquid may beintroduced into the space between the first optical element and thesecond optical element, and a lens, which has a concave curved surfaceas the lower surface (surface opposed to the first optical element), maybe used as the second optical element. Even in the case of such anarrangement, it is possible to maintain the characteristic of theprojection optical system PL by providing the removing unit to removeany foreign matter in the space inside of the concave surface portion.

In the embodiments described above, the liquid supply mechanism 10 isconstructed such that the two types of the first and second liquids LQ1,LQ2 are mixed in the mixing unit 19, and the liquid LQ, which isprepared by the mixing unit 19, is supplied to the image plane side ofthe projection optical system PL. However, it is of course possible toprovide such an arrangement that a plurality of arbitrary liquids ofthree or more types are mixed in the mixing unit 19, and the liquid LQprepared by the mixing unit 19 is supplied.

Alternatively, the liquid supply mechanism 10 may supply one type ofliquid (liquid having a refractive index higher than the refractiveindex of the first optical element LS1) without mixing the plurality oftypes of liquids. In this case, the liquid supply mechanism 10 isconstructed to have no mixing unit 19.

The liquid LQ, which is supplied by the liquid supply mechanism 10,includes, for example, predetermined liquids having C—H bond and O—Hbond such as isopropanol and glycerol, and predetermined liquid (organicsolvents) such as hexane, heptane, decane, and the like. Alternatively,it is also allowable to use those obtained by mixing two or morearbitrary liquids of the predetermined liquids. Further alternatively,it is also allowable to use those obtained by adding (mixing) thepredetermined liquid to pure water. Further alternatively, the liquidLQ, which is supplied by the liquid supply mechanism 10, may includethose obtained by adding (mixing) a base or an acid for liberating anionor cation such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄ ²⁻, PO₄ ²⁻, and the like to purewater. Further alternatively, it is also allowable to use those obtainedby adding (mixing) fine particles of Al oxide or the like to pure water.The ArF excimer laser beam is transmissive through the liquid LQ asdescribed above. As for the liquid LQ, it is preferable to use those inwhich the light absorption coefficient is small, the properties such asthe refractive index scarcely depend on the temperature, and the liquidLQ is stable against the resist coated on the surface of the substrate Pand the projection optical system PL.

Those having refractive indexes of about 1.6 to 1.8 may be used as theliquid LQ. Further, as for the first optical element LS1, any materialhaving a refractive index (for example, not less than 1.6) higher thanthose of silica glass and calcium fluoride may be used to form the firstoptical element LS1.

In the embodiments described above, the liquid immersion area LR isformed with the liquid having the refractive index higher than therefractive index of the first optical element LS1. However, there is nolimitation thereto. For example, a liquid having a refractive indexlower than the refractive index of the first optical element LS1 may beused. For example, a lens made of silica glass may be used as the firstoptical element LS1, and pure water may be used as the liquid LQ. In thecase of such an arrangement, the total reflection tends to occur whenthe angle of inclination of the light component of the light flux,especially the outermost beam of the light flux, with respect to theoptical axis (or NA) is increased, the light flux being allowed to comefrom the first optical element LS1 into the interface between the firstoptical element LS1 and the liquid LQ, and the light component beinginclined with respect to the optical axis AX. Therefore, thearrangement, in which the surface of the optical element included in theprojection optical system to make contact with the liquid is the concavesurface, especially the concave curved surface, is effective regardlessof the refractive index of the liquid LQ with respect to the refractiveindex of the optical element, because it is possible to lower the angleof incidence into the interface between the liquid and the opticalelement.

In the first to third embodiments described above, the ArF excimer laseris used as the exposure light beam EL. However, as described above, itis possible to adopt various types of exposure light beams (exposurebeams) including, for example, the F₂ laser. As for the liquid LQ to besupplied from the liquid supply mechanism 10, any optimum liquid can beappropriately used depending on, for example, the exposure light beam(exposure beam) EL, the numerical aperture of the projection opticalsystem PL, and the refractive index of the first optical element LS1with respect to the exposure light beam EL.

In the first to third embodiments described above, at least a part ofthe liquid LQ recovered by the liquid recovery mechanism 20 is returnedto the liquid supply mechanism 10. However, all of the liquid, which isrecovered by the liquid recovery mechanism 20, may be discarded, and thenew and clean liquid LQ may be supplied from the liquid supply mechanism10. The structure of the liquid immersion mechanism 1 including, forexample, the nozzle member 70 is not limited to the above. It is alsopossible to use those described, for example, in European PatentPublication No. 1420298 and International Publication Nos. 2004/055803,2004/057589, 2004/057590, and 2005/029559.

In the first to third embodiments described above, the detection unit 50is provided. However, the detection unit 50 may be omitted, and it isalso allowable to judge that the bubble (foreign matter) is absent inthe space inside of the concave surface portion 2 on the basis of thecompletion of the removing operation performed by the removing unit 40.

In the third embodiment described above, the removing unit 40 may bearranged for the substrate stage PST1.

In the first to third embodiments described above, the explanation hasbeen made about the case in which the refractive index of the firstoptical element LS1 with respect to the exposure light beam EL issmaller than the numerical aperture NA of the projection optical systemPL. However, the optical element such as the first optical element LS1,which has the concave surface portion 2, can be also adopted when therefractive index of the optical element with respect to the exposurelight beam is larger than the numerical aperture NA of the projectionoptical system PL. Also in this case, it is possible to adapt theremoving unit as explained in the first to third embodiments.

When the numerical aperture NA of the projection optical system is largedue to the use of the liquid immersion method as described above, it isdesirable to use the polarized illumination, because the image formationperformance is deteriorated due to the polarization effect in some caseswith the random polarized light which has been hitherto used as theexposure light beam. In this case, it is appropriate that the linearpolarized illumination, which is adjusted to the longitudinal directionof the line pattern of the line-and-space pattern of the mask (reticle),is effected so that the diffracted light of the S-polarized lightcomponent (TE-polarized light component), i.e., the component in thepolarization direction along with the longitudinal direction of the linepattern is dominantly allowed to outgo from the pattern of the mask(reticle). When the space between the projection optical system PL andthe resist applied to the surface of the substrate P is filled with theliquid, the diffracted light of the S-polarized light component(TE-polarized light component), which contributes to the improvement inthe contrast, has the high transmittance on the resist surface, ascompared with the case in which the space between the projection opticalsystem PL and the resist applied to the surface of the substrate P isfilled with the air (gas). Therefore, it is possible to obtain the highimage formation performance even when the numerical aperture NA of theprojection optical system exceeds 1.0. Further, it is more effective toappropriately combine, for example, the phase shift mask and the obliqueincidence illumination method or the like (especially the dipoleillumination method) adjusted to the longitudinal direction of the linepattern as disclosed in Japanese Patent Application Laid-open No.6-188169. In particular, the combination of the linear polarizedillumination method and the dipole illumination method is effective whenthe periodic direction of the line-and-space pattern is restricted toone predetermined direction and when the hole pattern is clustered inone predetermined direction. For example, when a phase shift mask of thehalf tone type having a transmittance of 6% (pattern having a half pitchof about 45 nm) is illuminated by the linear polarized illuminationmethod and the dipole illumination method in combination, the depth offocus (DOF) can be increased by about 150 nm as compared with the use ofthe random polarized light provided that the illumination a, which isprescribed by the circumscribed circle of the two light fluxes forforming the dipole on the pupil plane of the illumination system, is0.95, the radius of each of the light fluxes at the pupil plane is 0.125σ, and the numerical aperture of the projection optical system PL isNA=1.2.

It is also effective to adopt a combination of the linear polarizedillumination and the small σ illumination method (illumination methodwherein the σvalue, which indicates the ratio between the numericalaperture NAi of the illumination system and the numerical aperture NApof the projection optical system, is not more than 0.4).

For example, when the ArF excimer laser is used as the exposure lightbeam, and the substrate P is exposed with a fine line-and-space pattern(for example, line-and-space of about 25 to 50 nm) by the projectionoptical system PL having a reduction magnification of about ¼, then themask M acts as a polarizing plate due to the Wave guide effect dependingon the structure of the mask M (for example, the pattern fineness andthe thickness of chromium), and the diffracted light of the S-polarizedlight component (TE-polarized light component) outgoes from the mask Min an amount larger than that of the diffracted light of the P-polarizedlight component (TM-polarized light component) which lowers thecontrast. In this case, it is desirable to use the linear polarizedillumination as described above. However, even when the mask M isilluminated with the random polarized light, it is possible to obtainthe high resolution performance even when the numerical aperture NA ofthe projection optical system PL is large.

When the substrate P is exposed with an extremely fine line-and-spacepattern on the mask M, there is such a possibility that the P-polarizedlight component (TM-polarized light component) is larger than theS-polarized light component (TE-polarized light component) due to theWire Grid effect. However, for example, when the ArF excimer laser isused as the exposure light beam, and the substrate P is exposed with aline-and-space pattern larger than 25 nm by the projection opticalsystem PL having a reduction magnification of about ¼, then thediffracted light of the S-polarized light component (TE-polarized lightcomponent) outgoes from the mask M in an amount larger than that of thediffracted light of the P-polarized light component (TM-polarized lightcomponent). Therefore, it is possible to obtain the high resolutionperformance even when the numerical aperture NA of the projectionoptical system PL is large.

Further, it is also effective to use the combination of the obliqueincidence illumination method and the polarized illumination method inwhich the linear polarization is effected in the tangential(circumferential) direction of the circle having the center of theoptical axis as disclosed in Japanese Patent Application Laid-open No.6-53120, without being limited to only the linear polarized illumination(S-polarized illumination) adjusted to the longitudinal direction of theline pattern of the mask (reticle). In particular, when the pattern ofthe mask (reticle) includes not only the line pattern extending in onepredetermined direction, but the pattern also includes the line patternsextending in a plurality of different directions in a mixed manner(line-and-space patterns having different periodic directions arepresent in a mixed manner), then it is possible to obtain the high imageformation performance even when the numerical aperture NA of theprojection optical system is large, by using, in combination, the zonalillumination method and the polarized illumination method in which thelight is linearly polarized in the tangential direction of the circlehaving the center of the optical axis, as disclosed in Japanese PatentApplication Laid-open No. 6-53120 as well. For example, when a phaseshift mask of the half tone type having a transmittance of 6% (patternhaving a half pitch of about 63 nm) is illuminated by using, incombination, the zonal illumination method (zonal ratio: 3/4) and thepolarized illumination method in which the light is linearly polarizedin the tangential direction of the circle having the center of theoptical axis, the depth of focus (DOF) can be increased by about 250 nmas compared with the use of the random polarized light provided that theillumination a is 0.95 and the numerical aperture of the projectionoptical system PL is NA=1.00. In the case of a pattern having a halfpitch of about 55 nm and a numerical aperture of the projection opticalsystem NA=1.2, the depth of focus can be increased by about 100 nm.

In addition to the various types of the illumination methods asdescribed above, it is also effective to adapt, for example, theprogressive multi-focal exposure method disclosed in Japanese PatentApplication Laid-open Nos. 4-277612 and 2001-345245, and themultiwavelength exposure method to obtain an effect equivalent to thatof the multi-focal exposure method by a multiwavelength (for example,two wavelengths) exposure light beam.

It is also allowable that the first optical element LS1 is tightly fixedso that the first optical element LS1 is not moved, without allowing thefirst optical element LS1 to be exchangeable. In this case, anexchangeable optical member may be arranged between the substrate P(image plane) and the first optical element LS1 having the curved lowersurface T1.

The substrate P, which is usable in the respective embodiments describedabove, is not limited to the semiconductor wafer for producing thesemiconductor device. Those applicable include, for example, the glasssubstrate for the display device, the ceramic wafer for the thin filmmagnetic head, the master plate (synthetic silica glass, silicon wafer)for the mask or the reticle to be used for the exposure apparatus, andthe like. In the embodiment described above, the light-transmissive typemask (reticle) is used, in which the predetermined light-shieldingpattern (or phase pattern or dimming or light-reducing pattern) isformed on the light-transmissive substrate. However, in place of such areticle, as disclosed, for example, in U.S. Pat. No. 6,778,257, it isalso allowable to use an electronic mask on which a transmissivepattern, a reflective pattern, or a light-emitting pattern is formed onthe basis of the electronic data of the pattern to be subjected to theexposure.

As for the exposure apparatus EX, the present invention is alsoapplicable to the scanning type exposure apparatus (scanning stepper)based on the step-and-scan system for performing the scanning exposurewith the pattern of the mask M by synchronously moving the mask M andthe substrate P as well as the projection exposure apparatus (stepper)based on the step-and-repeat system for performing the full fieldexposure with the pattern of the mask M in a state in which the mask Mand the substrate P are allowed to stand still, while successivelystep-moving the substrate P.

As for the exposure apparatus EX, the present invention is alsoapplicable to the exposure apparatus based on the system in which thefull field exposure is performed on the substrate P by a projectionoptical system (for example, the dioptric type projection optical systemhaving a reduction magnification of ⅛ and including no catoptricelement) with a reduction image of a first pattern in a state in whichthe first pattern and the substrate P are allowed to substantially standstill. In this case, the present invention is also applicable to thefull field exposure apparatus based on the stitch system in which thefull field exposure is further performed thereafter on the substrate Pby partially overlaying a reduction image of a second pattern withrespect to the first pattern by the projection optical system in a statein which the second pattern and the substrate P are allowed tosubstantially stand still. As for the exposure apparatus based on thestitch system, the present invention is also applicable to the exposureapparatus based on the step-and-stitch system in which at least twopatterns are partially overlaid and transferred on the substrate P, andthe substrate P is successively moved.

The present invention is also applicable to the twin-stage type exposureapparatus. The structure and the exposure operation of the twin-stagetype exposure apparatus are disclosed, for example, in Japanese PatentApplication Laid-open Nos. 10-163099 and 10-214783 (corresponding toU.S. Pat. Nos. 6,341,007, 6,400,441, 6,549,269, and 6,590,634), JapanesePatent Application Laid-open No. 2000-505958 (PCT) (corresponding toU.S. Pat. No. 5,969,441), and U.S. Pat. No. 6,208,407. The disclosuresthereof are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

In the first to third embodiments described above, the exposureapparatus, in which the space between the projection optical system PLand the substrate P is locally filled with the liquid, is adopted.However, the present invention is also applicable to such an exposureapparatus that the exposure is performed for a substrate in a state inwhich the entire surface of the substrate for exposure is immersed inthe liquid, as disclosed, for example, in Japanese Patent ApplicationLaid-open Nos. 6-124873 and 10-303114 and U.S. Pat. No. 5,825,043. Thestructure and the exposure operation of such a liquid immersion exposureapparatus are described in detail in U.S. Pat. No. 5,825,043. Thecontents of the description in this United States patent document areincorporated herein by reference within a range of permission of thedomestic laws and ordinances of the state designated or selected in thisinternational application.

As for the type of the exposure apparatus EX, the present invention isnot limited to the exposure apparatus for the semiconductor deviceproduction for exposing the substrate P with the semiconductor devicepattern. The present invention is also widely applicable, for example,to the exposure apparatus for producing the liquid crystal displaydevice or for producing the display as well as the exposure apparatusfor producing, for example, the thin film magnetic head, the imagepickup device (CCD), the reticle, or the mask.

When the linear motor is used for the substrate stage PST and/or themask stage MST, it is allowable to use any one of those of the airfloating type based on the use of the air bearing and those of themagnetic floating type based on the use of the Lorentz's force or thereactance force. Each of the stages PST, MST may be either of the typein which the movement is effected along the guide or of the guidelesstype in which no guide is provided. An example of the use of the linearmotor for the stage is disclosed in U.S. Pat. Nos. 5,623,853 and5,528,118. The contents of the descriptions in the literatures areincorporated herein by reference respectively within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

As for the driving mechanism for each of the stages PST, MST, it is alsoallowable to use a plane motor in which a magnet unit provided withtwo-dimensionally arranged magnets and an armature unit provided withtwo-dimensionally arranged coils are opposed to one another, and each ofthe stages PST, MST is driven by means of the electromagnetic force. Inthis case, any one of the magnet unit and the armature unit is connectedto the stage PST, MST, and the other of the magnet unit and the armatureunit is provided on the side of the movable surface of the stage PST,MST.

The reaction force, which is generated in accordance with the movementof the substrate stage PST, may be mechanically released to the floor(ground) by a frame member so that the reaction force is not transmittedto the projection optical system PL, as described in Japanese PatentApplication Laid-open No. 8-166475 (U.S. Pat. No. 5,528,118). Thecontents of the descriptions in U.S. Pat. No. 5,528,118 are incorporatedherein by reference within a range of permission of the domestic lawsand ordinances of the state designated or selected in this internationalapplication.

The reaction force, which is generated in accordance with the movementof the mask stage MST, may be mechanically released to the floor(ground) by a frame member so that the reaction force is not transmittedto the projection optical system PL, as described in Japanese PatentApplication Laid-open No. 8-330224 (U.S. Pat. No. 5,874,820). Thedisclosure of U.S. Pat. No. 5,874,820 is incorporated herein byreference within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

As described above, the exposure apparatus EX according to theembodiment of the present invention is produced by assembling thevarious subsystems including the respective constitutive elements asdefined in claims so that the predetermined mechanical accuracy, theelectric accuracy, and the optical accuracy are maintained. In order tosecure the various accuracies, those performed before and after theassembling include the adjustment for achieving the optical accuracy forthe various optical systems, the adjustment for achieving the mechanicalaccuracy for the various mechanical systems, and the adjustment forachieving the electric accuracy for the various electric systems. Thesteps of assembling the various subsystems into the exposure apparatusinclude, for example, the mechanical connection, the wiring connectionof the electric circuits, the piping connection of the air pressurecircuits, and the like in correlation with the various subsystems. Itgoes without saying that the steps of assembling the respectiveindividual subsystems are performed before performing the steps ofassembling the various subsystems into the exposure apparatus. When thesteps of assembling the various subsystems into the exposure apparatusare completed, the overall adjustment is performed to secure the variousaccuracies as the entire exposure apparatus. It is desirable that theexposure apparatus is produced in a clean room in which, for example,the temperature, the cleanness and the like are managed.

As shown in FIG. 11, the microdevice such as the semiconductor device isproduced by performing, for example, a step 201 of designing thefunction and the performance of the microdevice, a step 202 ofmanufacturing a mask (reticle) based on the designing step, a step 203of producing a substrate as a base material for the device, a substrateprocessing step 204 of exposing the substrate with a pattern of the maskby the exposure apparatus EX of the embodiment described above anddeveloping the exposed substrate, a step of assembling the device(including a dicing step, a bonding step, and a packaging step) 205, aninspection step 206, and the like. The substrate processing step 204includes the process such as a step of removing the foreign matter and astep of inspecting the foreign matter as explained with reference toFIGS. 5 to 7 and 12.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to realize the liquidimmersion exposure in which the substrate is exposed through the liquid.Therefore, it is possible to produce the device having the devicepattern in which the resolution and the density are further enhanced.

1. An exposure apparatus which exposes a substrate by radiating anexposure light beam onto the substrate through a liquid, the exposureapparatus comprising: a projection optical system which includes aplurality of optical elements, at least one of the plurality of opticalelements having a concave surface portion making contact with theliquid; and a removing device which removes a foreign matter in a spaceinside of the concave surface portion, wherein the removing device has asuction port which sucks the foreign matter, and the removing device hasa driving system which moves the suction port relative to the concavesurface portion.
 2. The exposure apparatus according to claim 1, whereinthe concave surface portion is formed on a lower surface of a firstoptical element, included in the plurality of optical elements, andwhich is disposed closest to an image plane of the projection opticalsystem, and an optical path space formed between the first opticalelement and an object arranged on a side of an image plane of theprojection optical system and filled with the liquid.
 3. The exposureapparatus according to claim 2, wherein the removing device removes theforeign matter which is present in the liquid arranged in the spaceinside of the concave surface portion and which has a specific gravitysmaller than that of the liquid.
 4. The exposure apparatus according toclaim 1, wherein the foreign matter includes a bubble.
 5. The exposureapparatus according to claim 1, wherein the suction port is arranged ata highest position in the space inside of the concave surface portion orat a position near the highest position.
 6. The exposure apparatusaccording to claim 1, wherein the suction port is provided at a positionopposed to the concave surface portion.
 7. The exposure apparatusaccording to claim 1, wherein the suction port is provided outside anoptical path for the exposure light beam.
 8. The exposure apparatusaccording to claim 1, wherein the removing device performs suction in astate in which the suction port is moved closer to the concave surfaceportion by a predetermined distance.
 9. The exposure apparatus accordingto claim 1, wherein the removing device is provided on a movable memberwhich is movable on a side of an image plane of the projection opticalsystem.
 10. The exposure apparatus according to claim 9, wherein themovable member includes at least one of a first movable member movablewhile holding the substrate, and a second movable member provided with ameasuring device which performs measuring operation in relation to anexposure process.
 11. The exposure apparatus according to claim 1,further comprising: a nozzle member which has at least one of a supplyport which supplies the liquid and a recovery port which recovers theliquid, wherein: the removing device is provided for the nozzle member.12. The exposure apparatus according to claim 1, further comprising: adetection device which detects whether the foreign matter is present;and a control device which controls operation of the removing device onthe basis of a detection result of the detection device.
 13. Theexposure apparatus according to claim 1, further comprising a liquidsupply system which supplies the liquid, wherein the liquid supplysystem has a mixing device which mixes a plurality of types of liquids,and the liquid supply system supplies a mixed liquid mixed in the mixingdevice.
 14. The exposure apparatus according to claim 2, wherein arefractive index of the liquid is higher than a refractive index of thefirst optical element.
 15. The exposure apparatus according to claim 2,wherein a numerical aperture of the projection optical system is higherthan a refractive index of the first optical element.
 16. The exposureapparatus according to claim 1, wherein the concave surface portion is acurved surface.
 17. The exposure apparatus according to claim 1, whereinthe liquid includes at least one of glycerol and isopropanol.
 18. Theexposure apparatus according to claim 14, wherein a numerical apertureof the projection optical system is larger than the refractive index ofthe first optical element.
 19. The exposure apparatus according to claim14, wherein the first optical element is formed of silica glass orcalcium fluoride.
 20. The exposure apparatus according to claim 14,wherein the refractive index of the liquid with respect to the exposurelight beam is not less than 1.5.
 21. A method for producing a device,the method comprising: transferring a pattern onto a substrate with theexposure apparatus according to claim 1; and processing the substrate toform the device.
 22. An exposure method which exposes a substrate byradiating an exposure light beam onto the substrate via a liquid and anoptical element having a concave surface portion which makes contactwith the liquid, the exposure method comprising: removing a foreignmatter from the liquid in a space inside of the concave surface portionof the optical element with a removing device having a suction portwhich sucks the foreign matter, exposing the substrate by radiating theexposure light beam onto the substrate via the optical element and theliquid, and moving the suction port relative to the concave surfaceportion with a driving system.
 23. The exposure method according toclaim 22, wherein the substrate is exposed after and/or while removingthe foreign matter.
 24. The exposure method according to claim 22,further comprising: detecting the foreign matter present in the liquidin the space inside of the concave surface portion of the opticalelement.
 25. The exposure method according to claim 24, wherein theforeign matter is removed in accordance with a result of detection ofthe foreign matter.
 26. The exposure method according to claim 22,wherein a refractive index of the liquid is higher than a refractiveindex of the optical element with respect to the exposure light beam.27. The exposure method according to claim 26, wherein the exposurelight beam is radiated onto the substrate through the liquid by aprojection optical system which includes the optical element and whichhas a numerical aperture higher than the refractive index of the opticalelement.
 28. The exposure method according to claim 26, wherein therefractive index of the liquid with respect to the exposure light beamis not less than 1.5.
 29. A method for producing a device, comprising:exposing a substrate by the exposure method as defined in claim 22;developing the exposed substrate; and processing the developedsubstrate.